This invention relates to a process for the preparation of trifluoromethylbenzoyl chlorides, and bromides. The products are useful intermediates in the production of various dyestuffs and agricultural chemical products.
It is known to prepare trifluoromethylbenzoyl chloride by reaction of trifluoromethylbenzoic acid with thionyl chloride. The starting material for such reaction, trifluoromethylbenzoic acid may be prepared by several methods, each of which is a multistepped process involving relatively expensive starting materials and/or intermediates. Thus, for example, it is known to prepare trifluoromethylbenzoic acid by cyanation of bromo-benzotrifluoride, and hydrolysis of the resulting cyano-benzotrifluoride. In another known method, bromo-benzotrifluoride is reacted with magnesium and the resultant Grignard reagent is reacted with carbon dioxide to form trifluoromethylbenzoic acid. In still another method, xylene may be oxidized to toluic acid, esterified and the methyl group chlorinated and then fluorinated to yield trifluoromethylbenzoic acid.
Although the processes of the prior art are useful for the preparation of trifluoromethylbenzoyl chloride, it will be appreciated that improvements in the efficiency, economy of preparation and yield of the desired product are nevertheless desirable.
Accordingly, it is an object of this invention to provide an improved process for the preparation of trifluoromethylbenzoyl halides. It is a more specific object to provide a simple, direct process for the preparation of trifluoromethylbenzoyl chloride, based on the use of readily available, economical starting materials and reactants.